JP2007180850A - Photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing device capable of setting a photographic condition to an object which a photographer intends to photograph. <P>SOLUTION: An imaging means 20 acquires an image of the object before photographing the object. AN extraction means extracts a first partial image being in a preliminarily determined area, from the image acquired by the imaging means 20. A determination means 28 determines a photographic condition in accordance with a second partial image in an area which is a prescribed vector apart from the first partial image, in the image acquired by the imaging means 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photographing apparatus having an image recognition function such as tracking and face detection.

In a conventional photographing apparatus, a technique for tracking a subject such as a person based on a difference in hue may be used for each image obtained before photographing. In such a photographing apparatus, photographing conditions are set according to the tracked subject (for example, Patent Document 1).
JP 2005-55774 A

  However, in the method of Patent Document 1, the tracked subject is not always suitable for setting the shooting conditions. For example, when the hue of clothing worn by a person as a subject is significantly different from the surrounding hues, the clothing is tracked and shooting conditions are set according to the clothing. However, a person's face, not clothing, is appropriate as a subject for which shooting conditions are set. Thus, the subject to be tracked is not necessarily the same as the subject for which the photographer wants to set the photographing conditions.

  An object of the present invention is to provide a photographing apparatus capable of setting photographing conditions for a subject intended by a photographer.

In the photographing apparatus according to the first aspect, the imaging means acquires the image of the subject image before photographing the subject image. The extraction unit extracts a first partial image in a predetermined area from the image acquired by the imaging unit. The determining unit determines the imaging condition in accordance with the second partial image in an area separated from the first partial image by a predetermined vector in the image acquired by the imaging unit.
According to another aspect of the present invention, the tracking unit performs the tracking process based on the first partial image extracted by the extraction unit.

According to the third aspect of the present invention, the face extracting unit extracts a face image corresponding to a human face as a subject image from the image acquired by the imaging unit. The vector is a position vector connecting the first partial image extracted by the extracting unit and the face image extracted by the face extracting unit.
According to another aspect of the present invention, when the extraction unit or the face extraction unit fails to extract either the first partial image or the face image, the extraction unit or the face extraction unit executes the other extraction based on the vector.

  Shooting conditions can be set according to the subject intended by the photographer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of the photographing apparatus of the present invention. The camera 100 (photographing device) is, for example, a single-lens reflex digital camera, and has a camera body 102.
The photographic lens 104 is detachably attached to a lens mount 102 a formed on the front surface of the camera body 102 in order to guide the light flux from the subject to the camera body 102. The lens mount 102 a is provided with a communication contact (not shown) for exchanging various types of information between the camera body 102 and the photographing lens 104.

  The camera body 102 includes a quick return mirror 10, a finder screen 12, a penta roof prism 14, a half mirror 16, a re-imaging optical system 18, an area sensor 20 (imaging means), an eyepiece 22, and flash emission that irradiates a subject with flash emission. Unit 23, mechanical shutter 24, image sensor 26 composed of CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor) image sensor, etc., CPU 28 (extracting means, tracking means and determining means) and ROM 30. ing.

The quick return mirror 10 is rotatably provided on the optical axis OA. The quick return mirror 10 is disposed at an oblique position with respect to the optical axis OA when the subject is not photographed. The finder screen 12 is arranged at a position where it can receive the light beam incident from the quick return mirror 10 when not photographing.
The finder screen 12 is disposed at a position where the light beam imaged by the quick return mirror 10 is diffused and led to the half mirror 16 via the penta roof prism 14. The half mirror 16 is disposed at a position for guiding the light beam guided through the penta roof prism 14 to the re-imaging optical system 18 and the eyepiece lens 22, respectively. The re-imaging optical system 18 is disposed at a position where the light beam can be imaged on the area sensor 20 via the half mirror 16.

  The area sensor 20 is disposed at a rear position of the penta roof prism 14. The position of the area sensor 20 may be, for example, on the finder screen 12 as long as the light beam can be imaged before photographing of the subject is started. Further, in the case of a compact type digital camera, an image may be acquired by operating an image sensor used for shooting operation before shooting, and the acquired image may be output to the CPU.

  The area sensor 20 is composed of an image sensor such as a CCD. The area sensor 20 photoelectrically converts the light beam imaged by the re-imaging optical system 18 and outputs image signals of R (red), G (green), and B (blue) color components to the CPU 28. The eyepiece 22 is disposed at a position where the light beam guided from the half mirror 16 can be formed as a subject image. The photographer can check the composition and state of the subject by looking at the subject image formed by the eyepiece 22.

  The shutter 24 is disposed at a position where the light beam incident from the subject can be received when the quick return mirror 10 is retracted to the position indicated by the broken line in the drawing. The shutter 24 has a shutter film disposed at a position that blocks the optical path from the lens system 32 to the image sensor 26. The shutter 24 is driven by a shutter driver (not shown) and adjusts an exposure time during which the image sensor 26 is exposed by a light beam incident on the camera body 102 from the lens system 32. The shutter film is opened in order to secure an optical path from the lens system 32 to the image sensor 26 when imaging a subject. Instead of the mechanical shutter 24, the exposure time may be adjusted by an electronic shutter of the image sensor 26. Alternatively, the mechanical shutter 24 and the electronic shutter of the image sensor 26 may be used in combination.

The image sensor 26 is disposed at a position facing the lens system 32 via the shutter 24. The image sensor 26 is driven by an image sensor driver (not shown), photoelectrically converts the subject image formed by the lens system 32, and outputs the photoelectrically converted image to the CPU 28.
The taking lens 104 has a lens system 32 and a diaphragm 34. The lens system 32 includes a plurality of lenses including a focus lens that focuses on a subject and a zoom lens that zooms the subject image. The position of the focus lens and the zoom lens in the direction of the optical axis OA is adjusted by a lens driving circuit (not shown). The diaphragm 34 is driven by a diaphragm driver (not shown). The aperture value of the aperture 34 is adjusted to reduce the amount of light that has passed through the lens system 32.

  2 and 3 show images SP1 and SP2 sequentially output by the area sensor 20. FIG. Here, description will be made assuming that the subject is a person. The images SP1 and SP2 are output in this order. Each of these images is composed of 32 pixels horizontally and 24 pixels vertically. The number of pixels is not limited to a specific number. Further, the pixel shape is not a rectangle, and an image may be configured by combining circular or polygonal pixels. 2 and 3, i and j indicate coordinates in pixel units in the horizontal and vertical directions, respectively.

  2 indicates a position where a person exists in the image SP1, and reference numeral 38 indicates a tracking frame in which a subject (in this example, a person's clothes) is tracked by the tracking calculation described in FIG. Yes. A reference numeral 40 shown in FIG. 3 is a new tracking frame (first partial image) updated by the tracking calculation in the image SP2, and a reference numeral 42 is matched with a subject intended by the photographer (in this example, a human face). The exposure determination position (second partial image) referred to for determining the exposure condition is shown.

FIG. 4 shows an exposure condition determining operation in the first embodiment of the photographing apparatus. The operation shown in FIG. 4 is realized by the CPU 28 (extraction means, tracking means, and determination means) executing a program stored in the ROM 30.
First, in step S100, the CPU 28 waits for the photographer to press the release switch halfway. If half-press of the release switch is detected, the process proceeds to step S102. Step S100 is repeated until half-pressing of the release switch is detected.

  In step S102, the CPU 28 uses the image SP1 (FIG. 2) output from the area sensor 20 to calculate a predetermined feature amount C (sigmabBV, sigmagBV, sigmarBV) within the tracking frame 38. The tracking frame 38 may be set according to the subject (for example, a person's clothes) located at the center of the image SP1 when the release switch is half-pressed, or designated on the image SP1 by a user operation. May be. The CPU 28 calculates the feature amount C using the following arithmetic expression (1).

In Expression (1), BV is the APEX (Additive System of Photographic Exposure) value of the luminance value in the tracking frame 38, and i 'and j' are the coordinates of the pixel unit in the horizontal and vertical directions in the tracking frame 38, respectively. ing. Thereafter, the process proceeds to step S104.
In step S104, the CPU 28 starts tracking calculation using the image SP2 (FIG. 3) received from the area sensor 20 after the image SP1 described above. The CPU 28 divides the image SP2 into a plurality of pixel blocks, and calculates the feature amount C ′ using the arithmetic expression (1) for each pixel block. Thereafter, the process proceeds to step S106.

  In step S106, the CPU 28 sequentially compares the feature quantity C ′ with the above-described feature quantity C, and determines the pixel block of the feature quantity C ″ closest to the feature quantity C as a new tracking frame 40 (FIG. 3). The CPU 28 stores the feature value C ′ in the ROM 30 for the tracking calculation using the image subsequent to the image SP2. When there are a plurality of pixel blocks having the same feature value C ″, the CPU 28 The pixel block closest to the coordinates of the tracking frame 38 is determined as the tracking frame 40. Thereafter, the process proceeds to step S108.

  In step S108, the CPU 28 sets the exposure determination position 42 (FIG. 3). The CPU 28 sets a position separated from the tracking frame 40 by a predetermined position vector (x0, y0) as the exposure determination position 42. The position vector (x0, y0) varies according to the focal length of the zoom lens (FIG. 1). Thereafter, the process proceeds to step S110.

In step S110, the CPU 28 determines an exposure condition using the following arithmetic expression (2).
BV + SV = AV + TV (2)
In Expression (2), BV represents the APEX value of the luminance value at the exposure determination position 42, SV represents the APEX value of the sensitivity value of the image sensor 26, AV represents the APEX value of the aperture value, and TV represents the APEX value of the shutter speed. . The CPU 28 determines the aperture value AV and the shutter speed TV so as to satisfy the arithmetic expression (2). Thus, the exposure condition can be determined according to the exposure determination position 42. Thereafter, the process proceeds to step S112.

In step S112, the CPU 28 waits for the photographer to fully press the release switch. If it is detected that the release switch is fully pressed, the process proceeds to step S114. If it is not detected that the release switch is fully pressed, the process proceeds to step S104.
In step S114, the CPU 28 controls the shutter driver and the image sensor driver, respectively, drives the shutter 24 and the image sensor 26, and captures a subject image. Then, the exposure condition determination operation in the first embodiment of the photographing apparatus ends.

As described above, in the first embodiment, the exposure condition can be determined according to the exposure determination position 42 by setting the position separated from the tracking frame 40 by the position vector (x0, y0) as the exposure determination position 42. For this reason, it is possible to determine an exposure condition for a subject intended by the photographer (for example, a human face).
5 and 6 show a second embodiment of the photographing apparatus of the present invention. In this embodiment, following the image SP1 (FIG. 2), an image SP2 ′ shown in FIG. 5 is output from the area sensor 20 (imaging means) instead of the image SP2 (FIG. 3).

Reference numeral 44 shown in FIG. 5 is a new tracking frame (first partial image) updated by the tracking calculation in the image SP2 ′, and reference numeral 46 is a subject (in this example, a person) by the face detection calculation described in FIG. The face detection frame (face image) in which the detection of (face) is performed, and reference numeral 48 indicate exposure determination positions.
FIG. 6 shows an exposure condition determination operation in the second embodiment of the photographing apparatus. In this embodiment, the program stored in the ROM 30 for execution by the CPU 28 is different from that of the first embodiment of the image processing apparatus. FIG. 6 is the same as FIG. 4 except that step S106 of the first embodiment (FIG. 4) is replaced with steps S200 to S208.

Detailed description of the same processing as in FIG. 4 described above will be omitted. 6 is realized by the CPU 28 (extracting means, tracking means, face extracting means, and determining means) executing a program stored in the ROM 30.
First, steps S100 to S106 are executed, and after the tracking frame 44 (FIG. 5) is determined using the image SP2 ′, the process proceeds to step S200.

In step S200, the CPU 28 starts face detection calculation using the image SP2 ′. The CPU 28 divides the image SP2 ′ into pixel blocks having the same size as the template serving as a reference for face detection, and calculates a difference value between hue values of each pixel block and the template for each pixel. Thereafter, the process proceeds to step S202.
In step S202, the CPU 28 determines whether or not the difference value of the hue value is equal to or less than a predetermined threshold value. When it is detected that the difference value is equal to or smaller than the threshold value, that is, the face detection is successful, the process proceeds to step S204. On the other hand, when it is detected that the difference value exceeds the threshold value, that is, the face detection has failed, the process proceeds to step S210.

In step S <b> 204, the CPU 28 detects, as the face detection frame 46 (FIG. 5), a pixel block whose hue value difference value is equal to or less than a predetermined threshold value. Thereafter, the process proceeds to step S206.
In step S206, the CPU 28 sets the coordinates of the center of the face detection frame 46 as the exposure determination position 48 (FIG. 5). Thereafter, the process proceeds to step S208.

In step S <b> 208, the CPU 28 sets a vector from the tracking frame 44 to the face detection frame 46 as a position vector (x0 ′, y0 ′) and stores it in the ROM 30. Thereafter, steps S108 to S112 are executed, and the exposure determination operation in the second embodiment of the photographing apparatus is completed.
On the other hand, if it is detected in step S202 that the face detection has failed, in step S210, the CPU 28 determines the position vector (x0 ′, y0 ′) from the tracking frame 44 as in step S108 of FIG. Set the remote position as the exposure determination position. The position vector (x0 ′, y0 ′) is a position vector set by the CPU 28 when the face detection is successful. For this reason, even if face detection fails, the coordinates of the center of the face detection frame 46 can be estimated as the exposure determination position. Thereafter, steps S108 to S112 are executed, and the exposure determination operation in the second embodiment of the photographing apparatus is completed.

As described above, in the second embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, even when face detection fails, the coordinates of the center of the face detection frame 46 can be estimated as the exposure determination position. For this reason, exposure conditions can be determined in accordance with the subject intended by the photographer (for example, the face of a person).
In the above-described first and second embodiments, the example in which the aperture value AV and the shutter speed TV are determined in accordance with the exposure determination position has been described. The present invention is not limited to such an embodiment. Focusing by a focus lens, dimming of the flash light emitting unit 23, white balance setting, or the like may be performed on the exposure determination position.

In the first and second embodiments described above, an example in which a digital camera is used as the camera 100 has been described. The present invention is not limited to such an embodiment. A silver film type camera may be used as the camera 100.
In the second embodiment described above, the CPU 28 estimates the coordinates of the center of the face detection frame 46 shown in FIG. 5 as the exposure determination position based on the position vector (x0 ′, y0 ′) when face detection fails. An example was given. The present invention is not limited to such an embodiment. The CPU 28 may estimate the position of the tracking frame 44 as the exposure determination position based on the position vector (x0 ′, y0 ′) when the tracking calculation in the image SP2 ′ shown in FIG. 5 fails. With this estimation, even if the tracking calculation fails, the exposure condition can be determined in accordance with the subject intended by the photographer (in this example, a person's clothes).

  As mentioned above, although this invention was demonstrated in detail, said embodiment and its modification are only examples of this invention, and this invention is not limited to this. Obviously, modifications can be made without departing from the scope of the present invention.

  The present invention is applied to a photographing apparatus having an image recognition function such as tracking and face detection.

1 is a block diagram showing a first embodiment of a photographing apparatus of the present invention. It is explanatory drawing which shows the image output from the area sensor. It is explanatory drawing which shows the image output from the area sensor. It is a flowchart which shows the exposure condition determination operation | movement in 1st Embodiment of an imaging device. It is explanatory drawing which shows the image output from the area sensor. It is a flowchart which shows the exposure condition determination operation | movement in 2nd Embodiment of an imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Quick return mirror, 12 ... Finder screen, 14 ... Pentadaha prism, 16 ... Half mirror, 18 ... Re-imaging optical system, 20 ... Area sensor, 22 ... Eyepiece, 23 ... Flash light emission part, 24 ... Shutter, 26 ... Image sensor 28 ... CPU, 30 ... ROM, 32 ... Lens system, 34 ... Aperture, 100 ... Camera, 102 ... Camera body, 102a ... Lens mount, 104 ... Shooting lens

Claims (4)

Imaging means for obtaining an image of the subject image before photographing the subject image;
Extraction means for extracting a first partial image in a predetermined region from the image acquired by the imaging means;
An imaging apparatus comprising: a determination unit that determines an imaging condition in accordance with a second partial image in a region separated from the first partial image by a predetermined vector in the image acquired by the imaging unit. The imaging device according to claim 1,
An imaging apparatus comprising: tracking means for performing tracking processing based on the first partial image extracted by the extraction means. The imaging device according to claim 2,
A face extracting means for extracting a face image corresponding to the face of the person as the subject image from the image acquired by the imaging means;
The imaging apparatus according to claim 1, wherein the vector is a position vector connecting the first partial image extracted by the extracting unit and the face image extracted by the face extracting unit. In the imaging device according to claim 3,
The imaging apparatus according to claim 1, wherein the extraction unit or the face extraction unit executes the extraction of the other based on the vector when the extraction of either the first partial image or the face image fails.

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